Carpal tunnel syndrome is caused by a deleterious increase in pressure on the median nerve which passes through the carpal tunnel (or canal) in the hand, adjacent 10 the wrist. The deleterious increase in pressure, which is brought on by prolonged repetitive motion of the hand and digits, is often caused by inflammation or damage to tendons for the hand which pass through the carpal tunnel along with the median nerve. Pressure increases can also be caused by narrowing of the carpal canal and by generalized swelling of the structures in the hand.
The carpal tunnel is formed by the eight carpal bones of the hand adjacent the wrist, which bones are arranged in two rows forming a generally U-shaped inverted arch-like "tunnel" structure. The three large carpal bones of the proximal row (i.e., closest to the chest), beginning laterally (i.e., from the outside with the hand directed downward and the palm facing forward), are the scaphoid, lunate, and triquetrum; the smaller pisiform bone sits on the palmar surface of the triquetrum. The distal row, from lateral to medial, consists of the trapezium, trapezoid, capitate, and hamate carpal bones.
The vault of the carpal tunnel is formed by the carpal ligament and the flexor retinaculum. Nine tendons, their tendon sheaths, and the median nerve pass through the tunnel.
The carpal ligament is made of collagen and elastin and extends from the pisiformis and hamulus of hamate bones on the ulnar aspect of the tunnel to the tubercle (i.e., projection) of trapezium and the tubercle of the scaphoid bones on the radial (i.e. lateral) aspect of the carpal tunnel. The flexor retinaculum also stretches across the carpal tunnel and attaches to, on the medial aspect of the carpal tunnel, the pisiform bone and the hook of hamate, and, on the lateral aspect, the tubercle of the scaphoid and trapezium bones. The proximal border of the flexor retinaculum corresponds generally to the transverse skin crease at the base of the hand/wrist. The carpal ligament and flexor retinaculum, along with the carpal bones, form the restricted space through which the median nerve and several tendons pass.
Symptoms of carpal tunnel syndrome include tingling sensation in the hand, discomfort, numbness, and pain localized in the hand or radiating up the arm to the shoulder. All of these symptoms can occur during the day or can make the patients wake up at night. In advanced cases, there is atrophy and weakness of the thenar area of the hand which may weaken the grip and cause objects to fall out of the hand.
Conventional treatment of carpal tunnel syndrome is divided into surgical and conservative (non-invasive). Surgical treatment consists of making an incision on the palmar aspect of the hand and splitting the carpal ligament, thus partially opening the carpal tunnel and relieving the pressure. This procedure, while often successful, may have negative consequences, which include, but are not limited to, non-resolution of symptoms often requiring a second surgery, pain in the area of the scar, and injury to the superficial palmar branch of the median nerve causing persistent neurologic symptoms. Understandably, surgical treatment is often considered as a last option.
Conservative , non-invasive treatment includes immobilizing the hand and wrist, usually with a resting splint to maintain the hand in a neutral position (such as disclosed in U.S. Pat. No. 5,014,689), mechanical stretching of the carpal ligament (such as disclosed in U.S. Pat. No. 5,468,220), care provider administered massage, anti-inflammatory medications, cortisone injections, and avoidance of the daily activities which cause the symptoms, including a change in job. However, none of the known methods and devices provide for precise and controllable stretching of both the carpal ligament and the flexor retinaculum in a comfortable manner.
The objective of the present invention is to stretch the carpal ligament and the flexor retinaculum, as well as the superficial structures of the hand, in a safe manner under precise patient control. The new method and new appliance of prevention are inexpensive, prevent progression of carpal tunnel syndrome and provide relief from symptoms by increasing the cross sectional area of the carpal tunnel, thus decreasing compression on the median nerve and decreasing the resulting symptoms.
Controlled and monitored use of the appliance of the invention dynamically treats carpal tunnel syndrome through the application of pressure to large portions of the palm of the hand (in the thenar and hypothenar areas) while at the same time providing application of pressure, in the opposite direction, to a large portion of the dorsum of the hand with an air bladder. This novel procedure stretches the carpal ligament, the flexor retinaculum, and superficial structures of the hand in the palmar aspect of the hand, in a readily, safely controllable and comfortable manner.
Considering that the constitutions of the carpal ligament and the flexor retinaculum are soft tissue composed of collagen and elastin, stretching the carpal ligament and the flexor retinaculum is effective for decreasing compression on the median nerve by increasing the diameter of the tunnel and decreasing the rigidity of the retinaculum and the carpal ligament, thus alleviating the symptoms of carpal tunnel syndrome.